The present invention relates to a friction pad of a disk brake for use on a vehicle.
It is known in the art of disk brakes that a wear sensor is attached to a friction pad of a disk brake so that when the friction pad becomes worn to a predetermined extent, the wear sensor comes in contact with the disk to sound an alarm, thereby warning the user that the pad has become worn.
In a disk brake provided with such a wear detecting ability, a friction pad is composed of a backing plate and a lining material joined thereto. The backing plate is provided with a circular cylindrical projection. After being fitted with a wear sensor, the circular cylindrical projection is caulked (i.e., plastically deformed to clamp the sensor), thereby attaching the wear sensor to the backing plate.
The wear sensor attached in this way suffers, however, from the problem that the wear sensor undesirably rotates about the projection when subjected to force from the disk by coming into contact therewith. Further, when the wear sensor receives an axial force from the disk, the mounting portion of the wear sensor, which is secured to the backing plate, causes the radially enlarged portion of the projection (i.e., the head thereof) to be deformed. Consequently, the wear sensor is displaced apart from the surface of the backing plate, and this causes the position of the wear sensor to change, resulting in a change in characteristics enabling a correct alarm.